title: Local class switching in nonallergic rhinitis.
abstract: OBJECTIVE
  Patients with seasonal and/or persistent symptoms consistent with rhinitis but negative systemic testing for atopy can be diagnostically challenging. It has been postulated that such idiopathic or nonallergic rhinitis may be due to localized class switching and production of IgE in the nasal mucosa, a process which has been termed entopy by some authors. This review analyzes the available data to describe the current understanding of this process as it relates to nonallergic rhinitis.
  
  
  RESULTS
  Recent findings have demonstrated local IgE production in the nasal mucosa of patients who are otherwise negative on skin prick, intradermal, or serum testing for atopy. Comparable studies on nonatopic asthmatics have demonstrated evidence of local IgE class switching in lung respiratory mucosa. However, local class switching has only been unambiguously demonstrated in rhinitis patients when atopy is otherwise confirmed by routine testing.
  
  
  CONCLUSIONS
  There is significant evidence to indicate that local class switching in nonallergic rhinitis is possible; however, this has not been definitively proven. The question is raised as to whether local class switching can be demonstrated in nonallergic rhinitis and whether that class switching can be determined to be a specific affinity matured response. If present, a local IgE-mediated process is likely to define a cohort of nonallergic rhinitis more likely to respond to allergy-targeted therapies.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Virginia Health System, Charlottesville, Virginia 22908-0713, USA. spencercpayne@virginia.edu
authors.forename: Spencer C
authors.initials: SC
authors.lastname: Payne
authors.forename: Philip G
authors.initials: PG
authors.lastname: Chen
authors.forename: Larry
authors.initials: L
authors.lastname: Borish
mesh_terms: D001249:Asthma / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D003564:Cytidine Deaminase / Q000378:metabolism; D006801:Humans; D017578:Immunoglobulin Class Switching; D007073:Immunoglobulin E / Q000378:metabolism; D009297:Nasal Mucosa / Q000276:immunology; D012220:Rhinitis / Q000276:immunology*; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
chemical_list: D007073:Immunoglobulin E; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase